Method of dry distillation of alkalized waste liquor from the soda cellulose manufacture



Patented Aug. 9,1927.

UNITED STATES PATENT OFFICE}.

ERIK LUDVIG am, 01' DJ'URSHOLM, SWEDEN.

METHOD on DRY nrs'rr'nnarron or ALRALIZED 'wns'rn LIQUOR rnolii m sons onuunosn iranuraerunn.

No Drawing. Application filed June 4,1924, Serial no. 717,739, and in Sweden June a, 1923.

The present invention relates to an improvement on the processes previously described in my United States Patents No 1.196.290 of Aug. 29, 1916, and No. 1,347,713

of July 27, 1920, of dry distillation of alkalized waste liquor from the soda cellu lose manufacture, i. e. waste liquor to which a strong base, such as hydrate of lime, hasbeen added. According to the last mentioned patent the dry distillation is run to a temperature of about 500 0., so that all organic matters in the waste liquor are distilled over or charred, in order that it shall be possible to use the'residue for" the preparation of fresh boiling lye. When carrying out such dry distillation on amanufacturing scale itv has been found, however, that running the dryv distillation to such high temperature requires a long time and much fuel without yielding a correspondin economic gain in the way of chemical pro ucts.

Now, the present invention; has for its purpose-to provide a process according to which such dry distillation may be; carried out in such manner that while the distillation still yields the most valuable organic substances in the Waste liquorfiit is performed with a less consumption of fuel and thus at a less cost, and according to which the retort residue of the dry distillation is freed from the organic matters remaining in the same in a simple manner which renders said residue particularly adapted to be utilized for the preparationof fresh boiling lye and effects a saving of the lime necessary for such preparation.

The present process consists principally in that the dry distillation of waste liquor from the soda cellulose manufacture pre- -vi,ouly alkalized by an addition of hydrate of lime, isdiscontinued at a temperature of approximately 400 C. as soon asthe most valuable organic substances in the Waste liquor have distilled over, after which the residue in the retort,-preferably after cooling the dry distillation furnace so-that the chemical reactions in the same cease, is taken out and granulated or pulverized, and subjected to combustion so that the organic'substances remaining in the same are\consumed or char-red and the lime present in said residue -is burnt, partly or completely, to calcium monoxide, CaO. In th1s way'the advantage is attained that when the residue heated air. .verize' the soda coal and burn the same as powdered fuel with preheated air at a tem-" thus burnt is afterwards used for the prepsodium hydrate, so that the uantity of lime required. for regenerating tie soda in the residue to form fresh 1 e is correspondingly reduced. The destructlon of the organic substances remaining in the residue in the retortis also necessary for the reason that a very diflicultly filtered sludge is formed when preparing fresh; lye from the residue if it contains .uncharred organic substances. The combustion of the organic substances may be carried so far that not only the organic. substances but also carbon present in the retort residue is consumed.

' Theburning of the retort residue above referred to is preferably performed in a rotary furnace, for instance one of that type in which the waste liquor is usual y. burnt in a soda cellulose plant or a sulphate plant. It is-iinportant to obtain a high temperature at the final combustion of the retort The one Way is to granulate the soda coal.

preferably 'to pieces of 3 mm. size at the most, and burn the same at a tem erature of about 750 0., when approximate y threefourths of the lime in the soda coal become caustic. Such burning is most suitably performed in a rotary furnace and with pre- The other way is to finely pulerature of 1000 to 1200 when all lime ecomes caustic. melts but according as the lime becomes burnt it absorbs the melted soda, so that a solid tough mass is obtained. In a rotary furnace said mass forms balls during suc burning, which balls are easily dissolved, however, if they are introduced, without being cooled, in a mixing apparatus for preparation of lye. i

In respect of the details of the method the following may be observed: The dry distillation need, not be driven to a higher temperature than about 400 C. in order that all acetone, methyl-ethylketone, and methyl alcohol shall be distilled over. When the furnace is afterwards cooled, for instance by sprayingwater in a finely divided state into It is true that the soda or pulverized in the manners above set i about 300 o. the lime sludge 3 unslaked lime with the use of ordina ordinar is obtained than the same, to 250 to 300 (1., all chemical reactions in-the same cease and the oils are driven oft togetherwithth'e steam formed by the water, so that the furnace ma after- 5 wards be opened. without danger 0 exp sion. If partial cooling of the distillate is employed it is more suitable to use warm diluted condensatethus obtained, instead of.

water, for cooling the furnace. Such cool- 10 ing is most easily performed with such distillation furnaces in which the gases are kept in movement by means of a fan. When t e retort residue as been taken out from the furnace, it is suitably crushed and granulated forth, depending upon what method of burning it is desired to use. For the burnin a somewhat longer rota furnace than tfiat usually employed in sodacellulose plants is pre- 20 ferably used.

When the gases of combustion formed during the burning of the retort residue, are freefrom sulphur they may be used wit advantage for drying and preheating to ormed during the preparation of-fresh lye. If said sludge is dried with gases of combustion free from sulphur, the powder of calcium carbonate thus dried and preheatedmay be burnt to ing of therefore combustion for generatin or for preheating air an Q the same for drying the lime sludge.

I claim: 1. The process of treating waste 1i uor I from the soda cellulose manufacture, w 'ch consists inv alkalizing said waste the addition of h liquor b I drate of lime d ling said alkaliz waste liquor m t e presence of steam and interrupting such dry distillation at a temperature of about 400 C.,-.and afterwards removing and granulat- 1 spraying water in the same, and

removing and granulating the retort residue f about 750 C. so that all iler P distii 1,oas,oe1

ing the retort residue pieces of about? mm. size and burningsuch granulated residue at a temperature of about 750 C. so

that. allorganic substances in the same are consumed and the lime present in said residue is burnt to calcium monoxide.

2. The process of treating waste liquor from the soda cellulose manufacture, which consists in alkalizin said wasteliquor by the addition of by rate of lime, dry distilling said alkalized waste liquor in the resence of steam and interrupting such dry 'stillation at a tem rature of about 400 (3., cooling the dry distillation furnace, and afterwards removing and granulating the retort residue to pieces of about 3 mm. size and burning such granulated residue at a temperature of about 7 50 C. so that all orgame substances in the same are consumed and the lime present insaid residue is burnt to calcium monoxide.

3. The process of treating waste liquor h from the soda cellulose manufacture, WhlCh consists in alkalizing said waste liquor by the addition of 'hydrate of lime, dr distilling said alkalized waste liquor in t e presence of steam and interrupting such dry distillation at a temperature of about 400 0., cooling the dry distillation furnace by afterwards sue ieces of about 3 mm. size and burning granulated residue at a temperature of organic substances in the same are. consumed and the lime present in said residue is burnt to calcium monoxide. 1

4. The process of treating waste liquor from the soda cellulose manufacture, which consists in alkalizing said waste liquor by the addition by hydrate of l'me, dry distilling said alkalized waste liquor in the resence of steam and interrupting said dry distillation at a temperature of about 400 C., cooling the dry distlllation furnace, and

afterwards removing and granulating the retort residue to pieces of about 3 mm. size and burning said gr temperature of about 750 (1., so that all oramc substances and also carbon resent in t e residue are consumed and the e present in said residue is burnt to calcium mon-' oxide.

ERIK LUDVIG RINMAN.

anulated residue at a 

